Ordovician to Lower Silurian palynomorphs from the Sierras subandinas (Subandean ranges), northwestern Argentina: a preliminary report

Ordovician clastic sediments of the Central Andean Basin, northwestern Argentina, were deposited in a proto-Andean foreland basin on the western margin of Gondwana (Astini, 2003; Astini & Marengo, 2003). The Sierras Subandinas (Subandean Ranges) represent the outermost exposures of this Ordovician basin, where proximal environmental settings and their related palynological content are currently being analysed. These platform facies are exposed in the Eastern Cordillera, where palynological knowledge has increased remarkably in recent years (Rubinstein & Toro, 2001; Rubinstein, 2003). Deep marine facies are represented in the Puna, where palynological information is still meager, and involves only the Ordovician/ Silurian boundary (Rubinstein & Vaccari, 2004).